1. Field of the Art
The present invention relates to a composite printing apparatus which is capable of two different modes of printing, i.e., printing by means of type elements or type fonts, and dot-matrix printing with a matrix of dots.
Generally, a printing operation by means of character fonts (hereinafter referred to as "type-printing") is advantageous in printing quality, but disadvantageous due to its limited number of characters such as letters, numerals and symbols and its relatively low printing speed. In a dot-matrix printing operation, desired characters are printed by dot-matrix patterns defined by appropriate combinations of dots which are formed by print wires while a print head is moved at a suitable rate. Hence, a dot-matrix printer has substantially no limitation in the number of characters printable, and is comparatively high in printing speed. However, the dot-matrix printing with these advantages suffers a comparatively low level of printing quality.
In view of such circumstances in the prior art, a composite printing apparatus has been proposed, which is equipped with two printing units or assemblies for performing both of type-printing and dot-matrix printing. In such a printing apparatus known in the art, however, the two printing assemblies are selectively moved, as required, into a printing position on a print line along the platen of the printer so that a printing operation is effected by the selected one of the two printing assemblies.
2. Problem Solved by the Invention
Such composite printers require complicated arrangements for selective movements of the two printing assemblies to a printing position, and suffer a relatively low printing efficiency.